This invention relates to a reconstituted leather product and method of manufacturing reconstituted leather. More specifically, this invention relates to reconstituted leather and to a method of manufacture which utilizes scrap leather and other scrap material (e.g., scrap natural rubber) from the manufacture of leather goods (shoes) as its primary ingredients.
More generally, there has been a longstanding need to develop reconstituted leather utilizing leather scraps. Generally, prior efforts to manufacture reconstituted leather have employed the step of shredding scrap leather into a fibrous or powdered condition or have utilized synthetic fibers. Typically, a binder consisting of a gelatinaceous, vegetable, plastic, or asphalt material was utilized to form a slurry with the leather which was then formed into sheets or mats. Also, it was known that the matted material could be structurally reinforced by adhering reinforcing web of a suitable fabric to the back face of the material. Oftentimes, the reconstituted leather slurry was applied to a paper backing sheet or other semi-rigid material so as to afford sufficient strength to the material or to permit it to be formed in a desired configuration.
In many instances, however, the resulting reconstituted leather product did not emulate real leather in either appearance or feel. These prior reconstituted leather products had a synthetic or plastic feel to them, gave off plastic odors, and were oftentimes impervious to the transmission of air therethrough which, to a large degree, is particularly advantageous when the reconstituted leather product is utilized for shoe parts, articles of clothing, or upholstery fabric.
Reference may be made to such U.S. Pat. Nos. as: 52,737, 80,048, 170,962, 258,057, 656,869, 915,882, 1,269,905, 1,782,537, 1,677,125, 1,750,231, 1,757,993, 2,239,245, 2,383,598, 3,297,514, 3,298,851, and 4,287,252. These representative prior patents are in the same general field as the present invention.
Generally, reconstituted leather products suggested by the prior art have not been found entirely satisfactory because they differ from real leather in odor, feel, strength, and flexibility. Moreover, it has heretofore been difficult and expensive to attain a desired surface finish to both the finished face of prior reconstituted leather products and yet maintain a backside which is similar in appearance and feel to real leather. Still further, many of the prior art processes for manufacturing reconstituted leather required the user to take special steps to eliminate many of the chemicals present in tanned leather, such as chrome, alum, zinconium, and other chromatic salts which required special washing and leaching steps for the scrap, tanned leather prior to utilizing the leather in the manufacture of the reconstituted leather product.
Still other prior art processes required the leather to be ground into very fine particles, forming the particles into groups or globules, and then combining the globules of particles in an elastomerization process in which the binder was a material such as ethylene vinyl acetate copolymer, acrylate copolymer, acetoxylate polyethylene, or other polymeric binders.